Epoxyeicosatrienoic acids and the soluble epoxide hydrolase are determinants of pulmonary artery pressure and the acute hypoxic pulmonary vasoconstrictor response

Recent findings have indicated a role for cytochrome P-450 (CYP) epoxygenase-derived epoxyeicosatrienoic acids (EETs) in acute hypoxic pulmonary vasoconstriction (HPV). Given that the intracellular concentration of EETs is determined by the soluble epoxide hydrolase (sEH), we assessed the influence of the sEH and 11,12-EET on pulmonary artery pressure and HPV in the isolated mouse lung. In lungs from wild-type mice, HPV was significantly increased by sEH inhibition, an effect abolished by pretreatment with CYP epoxygenase inhibitors and the EET antagonist 14,15-EEZE. HPV and EET production were greater in lungs from sEH^-/- mice than from wild-type mice and sEH inhibition had no further effect on HPV, while MSPPOH and 14,15-EEZE decreased the response. 11,12-EET increased pulmonary artery pressure in a concentration-dependent manner and enhanced HPV via a Rho-dependent mechanism. Both 11,12-EET and hypoxia elicited the membrane translocation of a transient receptor potential (TRP) C6-V5 fusion protein, the latter effect was sensitive to 14,15-EEZE. Moreover, while acute hypoxia and 11,12-EET increased pulmonary pressure in lungs from TRPC6^+/- mice, lungs from TRPC6^-/- mice did not respond to either stimuli. These data demonstrate that CYP-derived EETs are involved in HPV and that EET-induced pulmonary contraction under normoxic and hypoxic conditions involves a TRPC6-dependent pathway.